- Gas System: PWS Long Stroke Piston System, 3-Setting Adjustable Gas System
- Muzzle Device: A2 Flash Hider
- Barrel Length: 16.1"
- Barrel: 416 Stainless Steel, Button Rifled
- Twist: 1:8
- Handguard: PWS free float Mlok™15” Handguard (1.6” width, 2.1” height)
- Upper Receiver: PWS Proprietary Piston Upper, 6061 extrusion, Anodized
- Charging Handle: Radian Raptor™Ambidextrous Charging Handle
- Weight: 4lbs 14oz
Note: The MK1 PRO upper will not work with a lower that has extended bolt catch/bolt releases that extends over the upper receiver- like the Phase 5 or B.A.D. style.